1. Field of the Invention
This invention relates to a method of adjusting a vehicle height and, more particularly, to a method of adjusting the height of a vehicle provided with a gas suspension system having a variable spring constant mechanism comprises from a plurality of gas chambers and a vehicle height adjusting function.
2. Description of the Prior Art
In a vehicle, for example, mounting an air suspension having a shock absorber disposed between a suspension arm and a vehicle body and the upper portion of which is surrounded by a housing and a diaphragm to form an air chamber for filling compressed air, the height of the vehicle can be adjusted or controlled by varying pressure in the air chamber.
In the vehicle provided with the air suspension, the relationship between time taken for adjusting or controlling the vehicle height and change in the vehicle height is as shown by a characteristic curve A in FIG. 1. Namely, when time T elapses from the beginning 0 of the vehicle height adjustment or the supply of the compressed air to the air chamber, a desired vehicle height H is attained. In this case, however, the desired vehicle height is not linearly attained, but the rise of the vehicle height after the beginning of the vehicle height adjustment is delayed by the effects of air compressibility, piping length between a pressure source and the air chamber, friction in each portion of the suspension or the like. And as pressure in the air chamber is gradually increased, the characteristic curve A draws a gentle curve and finally reaches the desired vehicle height H. Thus, when time T.sub.1 (&lt;T) elapses and the vehicle height becomes H.sub.1 (&lt;H), the adjustment of the vehicle height may be considered to be almost substantially completed.
To shorten the vehicle height adjusting time H (H.sub.1), the following actions can be taken;
(a) increasing the capacity of an air compressor, i.e., the pressure source, PA0 (b) installing a reservoir tank as the pressure source or increasing the capacity of the reservoir tank, PA0 (c) lessening the volumn of the air chamber, and PA0 (d) reducing the friction characteristics in each portion of the suspension or the like.